Question

If the potential difference across the plates of a capacitor is 10V and a dielectric having thickness 2m is introduced between the plates, calculate the potential difference after introducing the dielectric. The electric field strength is 2V/m.

(a) 4V

(b) 6V

(c) 8V

(d) 10V

This question was posed to me in an international level competition.

My doubt is from Composite Dielectric Capacitor in portion Capacitance and Capacitors of Basic Electrical Engineering

Answer 1

Correct choice is (b) 6V

To elaborate: When a dielectric is introduced between the plates of a capacitor, its potential difference decreases.

New potential difference= potential difference without dielectric-potential difference of dielectric = 10-2*2 = 6V.